This study will validate the real world results of polygene methylation detection in colorectal cancer in a large prospective community cohort. In this study, questionnaire survey and polygene methylation detection technology of colorectal cancer were used as preliminary screening methods, and colonoscopy was used as further validation examination method to screen colorectal cancer and precancerous lesions. The diagnosis and outcome of all lesions were based on colonoscopy and pathological examination.

1. The informed consent signed by shougang Community will be completed in the baseline period: Colorectal cancer risk factors assessment questionnaire, medical history collection, fecal immunochemical (FIT), carcinoembryonic antigen (CEA) blood test and blood bowel cancer gene methylation detection, for colorectal cancer gene methylation detection results more positive subjects and the result of the negative part of the subjects (n = 500), within 3 months after receiving the results complete colonoscopy.
2. Follow-up at 1, 2, 3, 4, and 5 years after baseline included: ① Central follow-up at 1, 3, and 5 years: history collection, colonoscopy, FIT test, and CEA examination; ② Telephone follow-up at the 2nd and 4th years: medical history was collected; (3) Survival outcome registration was performed in the fifth year; Follow-up history was collected at 1, 2, 3, 4, and 5 years after completion of baseline, and survival outcomes were registered at 5 years.
3. During the follow-up, the subjects were confirmed to be diagnosed with colorectal cancer by evaluation (colorectal cancer was diagnosed by colonoscopy), and the subjects who were treated after polyps or adenomas were found during colonoscopy also reached the study endpoint.

Inclusion Criteria:

1. Chronological age ≥40 years;
2. Full capacity for action;
3. After enrollment, the participants were able to complete the Colorectal Cancer Risk Factor Assessment Questionnaire and the annual follow-up interviews;
4. In the course of the study, the information related to tumor diagnosis in other hospitals can be timely fed back to the researchers;

Exclusion Criteria:

1. History of colorectal cancer and other malignant tumors;
2. Previous colorectal resection;
3. undergoing any cancer-related treatment;
4. Patients who have received major surgical treatment such as blood transfusion or transplantation within 3 months;
5. Participate in other interventional clinical investigators within 3 months;
6. Pregnant or lactating women;
7. Have autoimmune disease, hereditary disease, mental illness/disability, etc
8. Poor compliance, unable to complete the study.

18000 samples from Shougang community